The given question is incomplete. The complete question is
The thermite reaction, in which powdered aluminum reacts with iron oxide, is highly exothermic: . Use standard enthalpies of formation to find ΔH∘rxn for the thermite reaction. Express the heat of the reaction in kilojoules to four significant figures.
Answer: ΔH∘rxn for the thermite reaction is -851.5 kJ
Explanation:
The balanced chemical reaction is :
We have to calculate the enthalpy of reaction .
where,
We are given:
Putting values in above equation, we get:
ΔH∘rxn for the thermite reaction is -851.5 kJ
the oldest fossils on earth are 3.5 billion years
Answer is: <span>volume of balloon is </span>476,85 cm³.
density of air: d(air) = -0,0043 · 18,0°C + 1,2874.
d(air) = 1,21 kg/m³ = 1,21 · 10³/ 10⁶ = 0,00121 g/cm³.
m(balloon) = 0,577 g.
d(balloon) = d(air).
d(balloon) = m(balloon) ÷ V(balloon).
V(balloon) = m(balloon) ÷ d(balloon)
V(balloon) = 0,577 g ÷ 0,00121 g/cm³.
V(balloon) = 476,85 cm³.
Answer
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Hope this help!